Weeds infesting crops must be controlled or they reduce crop yields, hinder harvest operations and contaminate produce. Herbicides offer excellent weed control in various crops and cropping systems. Over dependence on one or few herbicides has resulted in the development of herbicide resistance in many weeds. Selective herbicides like atrazine, alachlor, metolachlor and simazine are contaminating surface and ground water due to high residual soil activity. Under such situations non selective herbicides offer excellent control of wide spectrum of weeds besides nil or very low soil residual activity. Exciting developments in plant biotechnology mark a new era in agriculture because herbicide-resistant crops (HRC's) are the first products of biotechnology to be grown on an economic scale. Worldwide spread of transgenic crops cultivation is 67.9 m. ha. In this 73% area (49.70 m. ha) is occupied by HRC'S. More than 40 HRC's are available for commercial cultivation in US, Canada, Australia, Europe, Brazil etc. Resistance in crops is available for different groups of herbicides like Sulfonylureas, Imidazolinones, Triazines, Glufosinates, Glyphosate etc. Roundup ready soybean, cotton and maize are popular in US. IWM approach is required to prolong the life of HRC's. Better weed control is obtained in HRC's when one or more of the practices are combined. Weed management in herbicide resistant crops should involve integrated weed management practices for retaining long-term potential of herbicides like glyphosate. Rotate HRC's with other crops, rotate herbicides, rotate HRC's that are tolerant to herbicide with different mode of action and other agronomic practices for effective weed control, better yields and prevention of herbicide resistance development.